Back rest for a chair



FIG. 1 is a perspective view showing the front and left side of a back rest for a chair which forms my new design, the broken lines in this and other figures showing other parts of a chair being for illustrative purposes only and forming no part of my design;

FIG. 2 is a front elevational view thereof; and,

FIG. 3 is a left side elevational view thereof, this view and the opposite right side elevational view being mirror images.

The short broken lines on the back rest in FIGS. 1–3 are understood to represent stitching. 

The ornamental design for a back rest for a chair, as shown and described. 